Thermoplastic resinous products containing flame retardants



This invention relates to flame-retardant compositions. Moreparticularly, this invention relates to flame-retardant compositionscomprising thermoplastic polymers containing a flame-retarding amount ofa compound having the formula where Q represents oxygen or sulfur and Yrepresents hydrogen, bromine or chlorine.

The use of various materials incorporated into thermoplastic resins inorder to improve the flame retardance thereof has been known in theprior art. Many compounds are commercially available for such a use,among them being chlorostyrene copolymers, chlorinated paraflin wax inadmixture with triphenyl stibine, chlorinated paraflins and aliphaticantimonyl compounds, as well as antimony oxide-chlorinated hydrocarbonmixtures. A drawback of these compounds, however, has been the fact thatgenerally a large amount, i.e. upwards of 35%, of additive must beincorporated into the resin in order to make it sufficiently flameretardant. Also these prior art additives tend to crystallize or oil outof the resin after a relatively short time of incorporation. We have nowfound a group of compounds which may be added to thermoplastic resins inrelatively small amounts and still result in the production ofsatisfactory flame retardant compositions and which will not crystallizeor oil out of the resin after incorporation therein.

The production of thermoplastic resin compositions which are flameretardant, i.e. have high resistance to burning, is of considerablecommercial importance. For example, such articles as castings, moldings,foamed or laminated structures and the like are required, or at leastdesired, to be resistant to fire and flame and to possess the ability toendure heat without deterioration. Typical illustrations of suchapplications can be found in castings for live electrical contacts whichshould not be ignited or deteriorated by heat and sparks. Structuralmembers such as pipes, wall coverings, wall paneling, windows and itemssuch as ash trays, waste baskets, fibers and the like are furtherexamples of products wherein flame retardance is desirable.

It is therefore an object of the present invention to provide novelflame retardant thermoplastic resin compositions.

It is a further object of the present invention to provide flameretardant compositions comprising thermoplastic polymers and aflame-retarding amount of a compound represented by Formula I, above.

These and further objects will become more apparent Mmmmmm 3,322,859Patented May 30, 1967 to those skilled in the art upon reading the moredetailed description set forth hereinbelow.

The thermoplastic polymers The theromplastic polymers into which theflame retardant agents may be incorporated to produce the novelcompositions of the present invention, are generally the vinyl typepolymers wherein the monomeric material is polymerized, by any knownmethod, via the vinyl unsaturation therein. Examples of the vinyl typepolymers which may be used to form our novel compositions are the vinylhalides, the vinylidene halides, the vinyl acetates, polyvinyl butyral,butadiene copolymers, acrylonitrile-butadiene-styrene polymers, theacrylonitriles, etc. Additionally and preferably, one may incorporatethe flame retard ant agents mentioned above into such polymers as thea-olefin polymers, such as the homopolymers and copolymers etc.containing, as the major constituent, ethylene, propylene, and the likeand acrylates and methacrylate polymers produced from monomers havingthe formula (II) o CH2=(LO wherein R is a hydrogen or methyl radical andR is a hydrogen or an alkyl radical having from 1 to 6 carbon atoms,inclusive. Examples of monomers represented by Formula II includeacrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate,n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butylacrylate, isobutyl acrylate, n-amyl acrylate, t-amyl acrylate, hexylacrylate and their corresponding alkyl methacrylates.

Additional examples of monomers which may be used to form thethermoplastic vinyl polymers encompassed by the present invention,polymerized either singularly or in combination with each other or withthe other compounds set forth hereinabove, are such monomers as theunsaturated alcohol esters, more particularly, the allyl, methallyl,vinyl, methvinyl, butenyl, etc., unsaturated esters of aliphatic andaromatic monobasic acids such, for instance, as acetic, propionic,butyric, crotonic, succinic, glutaric, adipic, maleic, fumaric, itaconicbenzoic phthalic, terephthalic, benzoylphthalic, etc., acids; thesaturated monohydric alcohol esters, e.g., the methyl, ethyl, propyl,isopropyl, butyl, sec-butyl, amyl, etc., esters of ethylenicallyunsaturated aliphatic monobasic acids illustrative examples of whichappear above; vinyl cyclic compounds (including monovinyl aromatichydrocarbons), e.g. styrene, 0-, m-, and p-chlorostyrenes,-bromostyrenes, -fluorostyrenes, -methylstyrenes, -ethylstyrenes,-cyanostyrenes, the various poly-substituted styrenes such, for example,as the various di-, tri-, and tetra-chlorostyrenes, -bromostyrenes,-fluorostyrenes, -methylstyrenes, -ethylstyrenes, -cyanostyrenes, etc.,vinyl pyridine, divinyl benzene, diallyl benzene, the various allylcyanostyrenes, the various alpha-substituted styrenes andalpha-substituted ring-substituted styrenes, e.g., alpha-methyl styrene,alpha-methylpara-methyl styrene, etc; unsaturated ethers, e.g., ethylvinyl ether, diallyl ether, etc.; unsaturated amides, for instance,N-allyl caprolactam, acrylamide, and N-substituted acrylamides, e.g.,N-methylol acrylamide, N-allyl acrylamide, N-methyl acrylamide, N-phenylacrylamide, etc.; unsaturated ketones, e.g., methyl vinyl ket-one,methyl allyl ketone, etc.; methylene malonic esters, e.g., methylenemethyl malonate, etc. and ethylene.

Other examples of monomers that can be used as polymers to form theresin portion of our novel flame-retardant compositions are the vinylhalides, more particularly, vinyl fluoride, vinyl chloride, vinylbromide, and vinyl iodide, and the various vinylidene compounds,including the vinylidene halides, e.g., vinylidene chloride, vinylidenebromide, vinylidene fluoride, and vinylidene iodide, other comonomersbeing added, if needed, in order to improve the compatibility andcopolymerization characteristics of the mixed monomers.

More specific examples of allyl compounds that can be polymerized touseful polymers, useful in the production of our novel flame-retardantcompositions, are allyl alcohol, methallyl alcohol, diallyl carbonate,allyl lactate, allyl alphahydroxyisobutyrate, allyl trichlorosilane,diallyl phthalate, diallyl methylgluconate, diallyl tartronate, diallyltartrate, diallyl mesaconate, the diallyl ester of muconic acid, diallylchlorophthalate, diallyl dichlorosilane, the diallyl ester ofendomethylene tetrahydrophthalic anhy dride, triallyl tricarballylate,triallyl cyanurate, triallyl isocyanurate, triallyl citrate, triallylphosphate, tetrallyl silane, tetrallyl silicate, hexallyl disiloxane,allyl diglycol carbonate, etc. Other examples of allyl compounds thatmay be employed are given, for example, in U.S. Patent No. 2,510,503,issued June 6, 1950.

These above mentioned monomers may be polymerized, copolymerized, etc.,in any known manner such as by free-radical generating catalysts,irradiation, anion and cation type catalysts and the like, said methodof polymerization forming no part of the present invention.

The flame retardant additives As mentioned above, we have discoveredthat various compounds represented by Formula I, above, which are stableto processing conditions, may be added to a thermoplastic resin toproduce resinous compositions having excellent flame-retardantproperties. These compounds may be incorporated into the thermoplasticresins in flameretarding amounts, i.e. generally amounts ranging fromabout by weight, to about 35%, by weight, preferably to by weight, basedon the weight of the polymer, have been found suflicient.

The flame-retardant compounds or additives may be incorporated into theresins by any known method. That is to say, the flame retardant additivemay be added to the resin by milling the resin and the additive on, for.

example, a two-roll mill, or in a Banbury mixer etc., or it i may beadded by molding or extruding the additive and resin simultaneously, orby merely blending it with the resin in powder form and thereafterforming the final desired article. Additionally, the flame-retardant maybe added during the resin manufacture, i.e., during the polymerizationprocedure by which the resin is made, provided the catalyst etc. andother-ingredients of the polymerization system are inert thereto.

The flame retardant additives set forth hereinabove may be produced inany known manner without varying from the scope of the presentinvention. An exemplary procedure for the production of compounds ofthis type comprises reacting a compound of the formula wherein X X eachrepresent chlorine or bromine, with a compound of the formula wherein Zrepresents hydrogen or an alkali metal and Q and Y are as set forthabove in regard to Formula I, to produce the desired compounds.

The reaction is preferably conducted in the presence of an organicsolvent and a salt-forming base at temperatures ranging from about 0 C.to about 200 C. at atmospheric pressure. A further and more completetrispiro [1,3,5,2,4,6-triazatriphosphorine-2,224,2:6,

2" -tris[ 1,3 ,2] benzodioxaphosphole] trispiro1,3,5,2,4,6-triazaphosphorine2,2 4,2" :6,

2-tris[1,3,2]benzodithiaphosphole],dodecachlorotrispiro[1,3,5,2,4,6-triazatriphosphorine- 2,2 4,26,2-tris-[ 1,3,2] benzodioxaphosphole]dodecachlorotrispiro-[1,3,5,2,4,6-triazaphosphorine- 2,2:4,2"6,2-tris[1,3,2]benzodithiaphosphole] dodecabromotrispiro 1,3 ,5,2,4,6-triazatriphosphorine- 2,2 4,2" 6,2"'-tris1,3,2]benzodioxaphosphole]dodecabromotrispiro[1,3,5,2,4,6-triazaphosphorine-2,224,2":6,2-tris[1,3,2]benzodithiaphosphole] and the like.

It should be noted that it is also within the scope of the presentinvention to incorporate such ingredients as plasticizers, dyes,pigments, stabilizers, antioxidants, antistatic agents and the like toour novel compositions.

The following examples are set forth for purposes of illustration onlyand are not to be construed as limitations on the present inventionexcept as set forth in the appended claims. All parts and percentagesare by weight unless otherwise specified.

Any appropriate flame retardance test may be used to determine the flameretardance properties of any specific compound. One test which isreasonably cfiicient is that designated as a modified version of ASTMtest D-635-56T. The specifications for this test are: a specimen, 5 inlength, 0.5 in width and 0.045" in thickness, is marked at the 1" and 4"lengths and is then supported with its longitudinal axis horizontal andits transverse axis inclined at 45 to the horizontal. A Bunsen burnerwith a 1" blue flame is placed under the free end of the strip and isadjusted so that the flame tip is just in contact with the strip. At theend of 30 seconds, the flame is removed and the specimen is allowed toburn. If the specimen does not continue to burn after the first ignitionit is immediately recontacted with the burner for another 30 secondperiod. If, after the two burnings, the strip is not burned to the 4"mark, the specimen is designated as "self-extinguishing orflame-retardant.

Example 1 Eighty parts of polyethylene and twenty (20) parts oftrispiro[1,3,5,2,4,6 triazatriphosphorine 2,24,2":6,2"-tris[1,3,2]benzodioxaphosphole] are milled together on a tworoll mill at about C. The resulting milled composition is molded intostrips 5" in length, 0.5 in width and 0.45 in thickness and said stripsare then subjected to an art recognized flame-retardance test. Thestrips pass the test and are therefore designated as flame-retardant.

Following the procedure of Example 1, the following examples werecarried out utlizing other flame retardant agents and variousthermoplastic resin polymers. The results of these examples are setforth in Table I below. In each instance the resultant compositionpassed the flame retardance test and was designated as flame and fireretardant. In the table, PE polyethylene', PP=polypropylene;PMMA=poly(methyl methacrylate); PA: poly(acrylic acid);AN=acrylonitrile; ST=styrene; and BD=butadiene; MMA=methyl methacrylate.

TABLE I Additive Ex. Thermoplastic Resin Percent Additive Q Y S H 20 CI25 0 Br 20 S Cl 25 S Br 15 O H 20 0 O1 20 0 Br 20 S H 25 S Cl 20 S Br 15O H 20 0 C1 15 0 Br 15 S H 25 S Cl 20 S Br 20 O H N 25 75%) and AN-ST(2590%).* 0 Cl do 30 0 Br 30 S H 20 S Cl 25 S Br 25 O H PA 25 S HMMA/AN/ 71/19/10 20 terpolymer.

*=U.S. Patent N 0. 2,439,202.

We claim:

1. A flame-retardant composition comprising a thermoplastic polymer ofan ethylenically unsaturated monomer and a flame retarding amount of acompound having the formula wherein Q is selected from the groupconsisting of oxygen and sulfur and Y is selected from the groupconsisting of hydrogen, bromine and chlorine.

2. A flame-retardant composition according to claim 1 wherein saidthermoplastic polymer is a polymer of an a-olefin.

3. A flame-retardant composition according to claim 1 wherein saidthermoplastic polymer is polyethylene.

4. A flame-retardant composition according to claim 1 wherein thethermoplastic polymer is a polymer of a compound having the formulawherein R is selected from the group consisting of hydrogen and a methylradical and R is selected from the group consisting of hydrogen and analkyl radical having from 1 to 6 carbon atoms, inclusive.

5. A flame-retardant composition according to claim 1 wherein thethermoplastic polymer is poly(methyl methacrylate) 6. A flame-retardantcomposition according to claim 1 wherein the thermoplastic polymer is amixture of (A) a butadiene-acrylonitrile oopolymer and (B) anacrylonitrile-styrene copolymer, the amount of A and B ranging fromabout 10-75% to 25%, by weight, respectively.

7. A flame-retardant composition according to claim 1 wherein saidcompound is trispiro[1,3,5,2,4,6-triazatriphosphorine2,2:4,2:6,2'-tris[1,3,2]benzodioxaphosphole].

8. A flame-retardant composition according to claim 1 wherein saidcompound is trispiro[1,3,5,2,4,6-triazatriphosphorine 2,2 4,2 6,2'-tris1,3,2]benzodithiaphosphole].

References Cited UNITED STATES PATENTS 2,681,295 6/ 1954 Hamalainen260-927 2,876,248 3/1959 Ratz et a1. 26 0-927 3,131,207 4/1964 Ratz260927 3,240,728 3/1966 Lund 260-2.5

MURRAY TILLMAN, Primary Examiner. GEORGE F. LESMES, Assistant Examiner.

1. A FLAME-RETARDANT COMPOSITION COMPRISING A THERMOPLASTIC POLYMER OFAN ETHYLENICALLY UNSATURATED MONOMER AND A FLAME RETARDING AMOUNT OF ACOMPOUND HAVING THE FORMULA
 6. A FLAME-RETARDANT COMPOSITION ACCORDINGTO CLAIM 1 WHEREIN THE THERMOPLASTIC POLYMER IS A MIXTURE OF (A) ABUTADIENE-ACRYLONITRILE COPOLYMER AND (B) AN ACRYLONITRILE-STYRENECOPOLYMER, THE AMOUNT OF A AND B RANGING FROM ABOUT 10-75F% TO 90-25%,BY WEIGHT, RESPECTIVELY.